Fluorine purification

Abstract

A method producing a volume of purified F 2 comprising removing HF from a F 2 feed and removing CF 4 from the F 2 feed, wherein a concentration of HF in the volume of purified F 2 is less than 1 ppm (v/v) and a concentration CF 4 in the volume of purified F 2 is less than 10 ppm (v/v).

1 . A continuous method of separating HF from a gas mixture having F 2  gas and HF gas to form a purified F 2  gas, comprising:
 flowing the gas mixture into a HF separation chamber that is cooled to a temperature sufficient to convert HF gas to HF liquid;   maintaining the temperature of the HF separation chamber at about −84° C. to about −80° C. by boiling a liquid refrigerant in fluid communication with the HF separation chamber:   converting HF gas to HF liquid in the HF separation chamber;   flowing the purified F 2  gas out of the HF separation chamber; and at the same time   removing HF liquid from the HF separation chamber.   
     
     
         2 . The method of  claim 1  further comprising a continuous flow of the gas mixture into the separation chamber. 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . The method of  claim 1 , wherein the coolant comprises CHF 3 . 
     
     
         6 . The method of  claim 1  further comprising recycling the refrigerant for heat exchange with the gas mixture in the HF separation chamber by condensing the refrigerant and returning the condensed refrigerant to the liquid refrigerant in fluid communication with the HF separation chamber; wherein the liquid refrigerant is heated by the heat exchange with the gas mixture to a degree sufficient to vaporize the liquid refrigerant coolant. 
     
     
         7 . The method of  claim 6 , wherein the refrigerant is condensed by contacting the vaporized refrigerant with a heat exchanger in fluid communication with a reflux coolant; and maintaining the reflux coolant at a temperature below the boiling point of the refrigerant. 
     
     
         8 . The method of  claim 1 , wherein the purified F 2  gas comprises less than 4000 ppm (v/v) HF. 
     
     
         9 . The method of  claim 8 , wherein the purified F 2  gas comprises less than 1000 ppm (v/v) HF. 
     
     
         10 . The method of  claim 1  further comprising maintaining the gas mixture within the HF separation chamber is at a pressure above about one atmosphere. 
     
     
         11 . The method of  claim 10 , wherein the gas mixture is maintained is at a pressure of at least two atmospheres. 
     
     
         12 . The method of  claim 1  further comprising
 flowing the purified F 2  gas from the first HF separation chamber cooled to a temperature sufficient to convert HF gas to HF liquid into a second separation chamber that is cooled to a temperature sufficient to convert HF gas to HF solid; and 
 flowing the purified F 2  gas out of the second HF separation chamber thereby separating the HF solid from the gas mixture. 
 
     
     
         13 . The method of  claim 12 , wherein the temperature sufficient to convert HF gas to HF solid is between about −180° C. and about −85° C. 
     
     
         14 . The method of  claim 12 , wherein the purified F 2  gas comprises less than 5 ppm (v/v) HF. 
     
     
         15 . The method of  claim 14 , wherein the purified F 2  gas comprises less than 1 ppm (v/v) HF. 
     
     
         16 . The method of  claim 12 , wherein the HF solid is separated from the gas mixture electrostatically. 
     
     
         17 . The method of  claim 16 , wherein the purified F 2  gas comprises less than about 0.5 ppm (v/v) HF. 
     
     
         18 . The method of  claim 17 , wherein the purified F 2  gas comprises less than about 0.1 ppm (v/v) HF. 
     
     
         19 . (canceled) 
     
     
         20 . A method of purifying a gas mixture, comprising a F 2  gas and a HF gas, to form a purified F 2  gas comprising:
 establishing a continuous flow of the gas mixture;   flowing the F 2  gas mixture into a first HF separation chamber that is cooled to a temperature sufficient to convert the HF gas to a HF solid;   separating the HF solid from the gas mixture in the first HF separation chamber;   diverting the flow of the gas mixture from the first HF separation chamber to a second HF separation chamber that is cooled to a temperature sufficient to convert the HF gas to a HF solid;   separating the HF solid from the gas mixture in the second HF separation chamber and concurrently warming the first HF separation chamber to a temperature sufficient to melt the HF solid and form a HF liquid; and   removing the HF liquid from the first HF separation chamber.   
     
     
         21 . The method of  claim 20 , wherein after the formation of solid HF in the second HF separation chamber, melting the HF solid from the first HF separation chamber, and removing the melted HF solid from the first HF separation chamber, the first HF separation chamber is cooled to a temperature sufficient to convert the HF gas to a HF solid and the flow of the gas mixture is diverted back to the first HF separation chamber; and thereafter HF liquid is removed from the second HF separation chamber. 
     
     
         22 . A method of separating CF 4  from a gas mixture comprising F 2  gas and CF 4  gas and less than 10 ppm (v/v) HF gas to form a purified F 2  gas, comprising:
 flowing the gas mixture into a CF 4  Separation Chamber that is cooled to a temperature sufficient to convert CF 4  gas to CF 4  liquid;   converting the CF 4  gas to CF 4  liquid;   flowing the purified F 2  gas out of the CF 4  Separation Chamber; and at the same time   removing CF 4  liquid from the CF 4  Separation Chamber.   
     
     
         23 . The method of  claim 22 , wherein the CF 4  liquid comprises CF 4  and F 2 ; further comprising distilling F 2  gas from the CF 4  liquid and flowing the distilled F 2  gas into the CF 4  Separation Chamber. 
     
     
         24 . The method of  claim 23 , wherein the CF 4  separation chamber is maintained at a temperature in the range of about −196° C. and about −128° C. 
     
     
         25 . The method of  claim 22 , wherein the purified F 2  gas comprises less than 50 ppm (v/v) CF 4 . 
     
     
         26 . The method of  claim 25 , wherein the purified F 2  gas comprises less than about 20 ppm (v/v) CF 4 . 
     
     
         27 . The method of  claim 26 , wherein the purified F 2  gas comprises less than about 10 ppm (v/v) CF 4 . 
     
     
         28 . A method of purifying a gas mixture, comprising a F 2  gas, a HF gas, and a CF 4  gas, to form a purified F 2  gas comprising:
 flowing the gas mixture into a HF separation chamber that is cooled to a temperature sufficient to convert the HF gas to a HF liquid;   maintaining the temperature of the HF separation chamber at about −84° C. to about −80° C. by boiling a liquid refrigerant in fluid communication with the HF separation chamber;   reducing a HF concentration in the gas mixture to less than about 10 ppm (v/v) HF; and then   flowing the gas mixture into a CF 4  separation chamber that is cooled to a temperature sufficient to convert the CF 4  gas to a CF 4  liquid;   reducing a CF 4  concentration in the gas mixture to less than about 100 ppm (v/v) CF 4 ; and   removing the purified F 2  gas from the CF 4  separation chamber.   
     
     
         29 . A method of manufacturing NF 3  comprising
 reacting a NH 3  gas with a purified F 2  gas, wherein the purified F 2  gas is obtained by the method of  claim 1 .   
     
     
         30 . The method of  claim 29 , wherein the purified F 2  gas contains less than 10 ppm (v/v) CF 4 ; and the purified F 2  gas is obtained from a gas mixture comprising a F 2  gas, a HF gas, and a CF 4  gas by:
 flowing the gas mixture into a HF separation chamber that is cooled to a temperature sufficiently low to convert the HF gas to a HF liquid;   separating the HF liquid from the gas mixture;   flowing the remaining gas mixture into a CF 4  separation chamber that is cooled to a temperature sufficiently low to convert the CF 4  gas to a CF 4  liquid;   separating the CF 4  liquid from the remaining gas mixture to form the purified F 2  gas; and   removing purified F 2  gas from the CF 4  separation chamber.   
     
     
         31 . A method of manufacturing NF 3  comprising reacting a NH 3  gas with a purified F 2  gas, wherein the purified F 2  gas is obtained by the method of  claim 20 . 
     
     
         32 . A method of manufacturing NF 3  comprising
 reacting a NH 3  gas with a purified F 2  gas, wherein the purified F 2  gas is obtained by the method of  claim 22 .   
     
     
         33 . A method of manufacturing NF 3  comprising reacting a NH 3  gas with a purified F 2  gas, wherein the purified F 2  gas is obtained by the method of  claim 28 . 
     
     
         34 . The method of  claim 28  further comprising recycling the refrigerant for heat exchange with the gas mixture in the HF separation chamber by condensing the refrigerant and returning the refrigerant to the liquid refrigerant in fluid communication with the HF separation chamber; wherein the refrigerant is heated by the heat exchange with the gas mixture to a degree sufficient to vaporize the refrigerant. 
     
     
         35 . The method of  claim 28 , wherein the CF 4  liquid comprises CF 4  and F 2 ; further comprising distilling F 2  gas from the CF 4  liquid and flowing the distilled F 2  gas into the CF 4  Separation Chamber.